| ( | 4 | − | x | − | 2 | ) | ( | 100 | + | 2 | x | ) | = | 300 |
| 方程左边 = | 4 | ( | 100 | + | 2 | x | ) | − | x | ( | 100 | + | 2 | x | ) | − | 2 | ( | 100 | + | 2 | x | ) |
| = | 4 | × | 100 | + | 4 | × | 2 | x | − | x | ( | 100 | + | 2 | x | ) | − | 2 | ( | 100 | + | 2 | x | ) |
| = | 400 | + | 8 | x | − | x | ( | 100 | + | 2 | x | ) | − | 2 | ( | 100 | + | 2 | x | ) |
| = | 400 | + | 8 | x | − | x | × | 100 | − | x | × | 2 | x | − | 2 | ( | 100 | + | 2 | x | ) |
| = | 400 | − | 92 | x | − | x | × | 2 | x | − | 2 | ( | 100 | + | 2 | x | ) |
| = | 400 | − | 92 | x | − | x | × | 2 | x | − | 2 | × | 100 | − | 2 | × | 2 | x |
| = | 400 | − | 92 | x | − | x | × | 2 | x | − | 200 | − | 4 | x |
| = | 200 | − | 96 | x | − | x | × | 2 | x |
| 200 | − | 96 | x | − | x | × | 2 | x | = | 300 |